Attention has been paid to a microchip which can perform a highly accurate analysis due to advantages such as a higher reaction rate, a higher yield to obtain a desired product, and a reduced amount of necessary reagent as compared to a chemical reaction in a beaker or a test tube.
When a chemical reaction or an electrolysis reaction of liquid is performed using the microchip, it is necessary to separate liquid from gas because a flow path may easily be blockaded by gaseous bubbles. As a microchip device which performs the gas liquid separation, a device having a structure as shown in FIGS. 22 to 24 has been proposed.
FIG. 22 is a perspective view of the microchip device, FIG. 23 is a plan view of the microchip with the cover of FIG. 22 removed, and FIG. 24 is a cross sectional view taken along a section line A-A in FIG. 23. As shown in FIG. 22, the microchip device 1 includes a microchip 3 and a cover 5 in a stacked arrangement on the microchip 3.
As shown in FIG. 23, on the surface upon which a cover 5 of the microchip 3 is stacked, a liquid flow path 9 for liquid to flow and a gas flow path 11 for gas to flow, which is shallower than the liquid flow path 9, are configured in parallel.
Both end parts of the liquid flow path 9 and both end parts of the gas flow path 11 are located at each of the four corners of the microchip 3. On the cover 5 are formed a first liquid port 13 connected to one end of the liquid flow path 9, a second liquid port 15 connected to the other end of the liquid flow path 9, a first gas port 17 connected to one end of the gas flow path 11, and a second gas port 19 connected to the other end of the gas flow path 11. Furthermore the central part of the liquid flow path 9 and the central part of the gas flow path 11 are closely contacted with each other to form a contacting section 7.
As shown in FIG. 24, in the cross sectional shape of the contacting section 7, a protrusion 10 is formed at interface between the central part of the liquid flow path 9 and the central part of the gas flow path 11. On the bottom surface of the gas flow path 11, a liquid repellent part 12 is formed, which is formed by a layer of a material having a liquid repellent property.
In the microchip device with the configuration described above, when liquid 21 is introduced from the first liquid port 13, the liquid 21 flows through the liquid flow path 9, and is exhausted from the second liquid port 15. In this case, by setting adequately the pressure for introducing the liquid 21, the liquid 21 is not over the protrusion 10 due to its surface tension, and a stable gas liquid interface K is formed as shown in FIG. 24.
Thus, gas in the liquid 21 is separated through the gas liquid interface K, and the separated gas is exhausted from the first gas port 17 and the second gas port 19 through the gas flow path 11.
Furthermore, when liquid is introduced from the first liquid port 13 and gas is introduced from the first gas port 17, the gas can also be smoothly absorbed through the gas liquid interface K due to negative pressure resulting from the flows (refer to, for example, Patent Document 1).
Moreover, conventionally, various distillation methods have been known which heat up and vaporize a mixed liquid including a plurality of components with different boiling temperatures, and condense a vapor containing mainly a lower boiling temperature component, thereby separating the components of the mixed liquid (refer to, for example, Patent Document 2).
Patent Document 1: Japanese Unexamined Patent Application, First Publication, No. 2005-169386 (pages 11 to 12, FIG. 1)
Patent Document 2: Japanese Unexamined Patent Application, First Publication, No. 2002-102601
However, in the configuration shown in FIG. 22 to FIG. 24, as the height of the gas liquid interface K is between the protrusion 10 and the cover 5, the height is low, and then an area of the gas liquid interface K is small, which results in a problem of a low value in gas liquid separation efficiency and gas absorption efficiency.
Furthermore, in a microchip such as a μTAS, a bio MEMS, and a micro reactor, there has been no microchip device known which can perform a distillation such as described in Patent Document 2.